• Advertisement

4JB1 Repair Questions

Get help fixing your Isuzu from other club members

4JB1 Repair Questions

Postby 4JB1TCR » Fri Sep 23, 2016 5:53 am

Hello from another continent! I am from Costa Rica, in central America.

I have been an Isuzu owner for some years now, I bought a beat up Amigo with the 2.6L gasoline engine (MU to most of you), and restored it to half decent conditions.

Now I have purchased a partially disassembled 4JB1-T. It is here that I need your help. I will paste what I wrote on a forum in the USA, which has much more limited knowledge of these engines.

Two weeks ago, I either did something stupid, or I scored a good deal, time will tell. I happened to come a across a cheap 4JB1 Turbo engine in one of my scrounging of the local classifieds. Now, cheap can be bad, or can be good.
This is what it looked like in the back off the LandCruiser on the way home.
Image
Image
And this is how it looks on the floor of the storage building at work.

Image
Image
Image

Failed Gasket.
Image
Image

Head:
Image
Now, the story behind this engine...

The fellow that I bought if off, is an older gentleman, stuck me as the honest sincere kind of guy, so I'll believe his story.

He had this in a 1992 Trooper, had it overhauled because it was tired. He spent a good lot of money on the overhaul.
When it was put back in the Trooper, he had trouble with having the coolant reservoir pressurize. He changed radiator cap, then the radiator, and the reservoir. In the end it was pressure from the cylinders leaking into the cooling system. The mechanic pulled the head.

Now, here is where it gets interesting.
The mechanics diagnostic was, that the wrong liners had been installed, and there was insufficient liner protrusion, to seal the headgasket properly, so rather than sinking more money into it, the poor man went a got a 4JG2.
Now, the manual states that the liners can be flush with the deck, or slightly projected, which these are. I haven't yet measured the exact projection. Furthermore, the fire rings on the failed gasket, show over-torque if anything.
Verdict?
Dunno!
Simply a botched head-gasket install?
Liners were not fully seated, and the head and gasket finished seating them, thus destroying the gasket?

I don't know.
Since the head had been checked, and it was not overheated since, and because the headgasket had visibly failed, I will probably skip sending the head off to be checked.


Now, since I wrote that, I have been examining further, and found lots of piston slop.
I can't for the life of me, get a Youtube video to embed, so here's the link
https://www.youtube.com/watch?v=u-74Sfy3sKs
I'll try to get some more pictures a bit later, but what is the recomendation? Go ahead and do a full rebuild if budget allows?

Thanks!
4JB1TCR
Isuzu Baby
 
Posts: 13
Joined: Wed Sep 07, 2016 11:19 pm
Age: 27
Country: Costa Rica
City: Pital
Vehicle: 1991 Amigo

Re: 4JB1 Repair Questions

Postby 4JB1TCR » Tue Sep 27, 2016 6:53 am

I see I may have posted this in the wrong subforum. Could the mods please put it in the proper place? Thanks!
4JB1TCR
Isuzu Baby
 
Posts: 13
Joined: Wed Sep 07, 2016 11:19 pm
Age: 27
Country: Costa Rica
City: Pital
Vehicle: 1991 Amigo

Re: 4JB1 Repair Questions

Postby geeves » Tue Sep 27, 2016 8:18 am

Now moved to engine faults
I do note looking at the head gasket severe corrosion around some of the water holes. Did they reuse the old gasket when they rebuilt the engine? That would raise the question about how long ago this was rebuilt and how well? The head looks ok but its not always easy to tell.
Sanding your knuckles before starting work can help. That way you cant skin them
User avatar
geeves
Site Admin
 
Posts: 8962
Joined: Sun May 10, 2009 1:36 pm
Location: Rangiora
Age: 63
Country: NZ
City: Rangiora
Vehicle: 94 bighorn 4jg2
2013 Subaru XV

Re: 4JB1 Repair Questions

Postby geeves » Tue Sep 27, 2016 9:26 am

Just looked at that video
A full dismantle is in order. Dont know yet what will be found but prepare for the worst
Just out of interest though the correct engine for a 92 trooper was a 4jg2 so a bit more info might be required
Sanding your knuckles before starting work can help. That way you cant skin them
User avatar
geeves
Site Admin
 
Posts: 8962
Joined: Sun May 10, 2009 1:36 pm
Location: Rangiora
Age: 63
Country: NZ
City: Rangiora
Vehicle: 94 bighorn 4jg2
2013 Subaru XV

Re: 4JB1 Repair Questions

Postby 4JB1TCR » Wed Sep 28, 2016 12:28 am

geeves wrote:Just looked at that video
A full dismantle is in order. Dont know yet what will be found but prepare for the worst
Just out of interest though the correct engine for a 92 trooper was a 4jg2 so a bit more info might be required

Thanks Geeves. I'm going to tear it apart as soon as I can for a full inspection. Right now I am beginning to wonder if the fabled rebuild ever happened, I kind of think it didn't. I was noticing the corrosion on the gasket too. There is no way the amount of wear on the cylinder walls, and the corrosion on the gasket, is going to happen on a recent overhaul. I have a feeling the mechanic stole the man's money and never rebuilt it, or the man invented the whole story.

Here is a close-up of the cylinder wall.
Image

I will keep updating this as I disassemble.

As to this engine being in a Trooper. I was originally a V6 gasoline engine, this one was put in back in 2005 from what I can dig up from documents on the national vehicle registry.
4JB1TCR
Isuzu Baby
 
Posts: 13
Joined: Wed Sep 07, 2016 11:19 pm
Age: 27
Country: Costa Rica
City: Pital
Vehicle: 1991 Amigo

Re: 4JB1 Repair Questions

Postby jellis » Wed Sep 28, 2016 10:26 am

much of a lip on the liner?
cheers, Josh
jellis
Isuzu Guru
 
Posts: 417
Joined: Sun May 10, 2009 10:23 am
Age: 26
Country: australia
City: sydney
Vehicle: 1992 isuzu mu 2" lift all round
33"x 12.5 federal's

Re: 4JB1 Repair Questions

Postby geeves » Wed Sep 28, 2016 12:51 pm

That looks like a factory chrome liner that has been honed. Its peeling at the top
Sanding your knuckles before starting work can help. That way you cant skin them
User avatar
geeves
Site Admin
 
Posts: 8962
Joined: Sun May 10, 2009 1:36 pm
Location: Rangiora
Age: 63
Country: NZ
City: Rangiora
Vehicle: 94 bighorn 4jg2
2013 Subaru XV

Re: 4JB1 Repair Questions

Postby 4JB1TCR » Thu Sep 29, 2016 6:22 am

jellis wrote:much of a lip on the liner?


No way to measure, but enough to easily feel with a finger.
4JB1TCR
Isuzu Baby
 
Posts: 13
Joined: Wed Sep 07, 2016 11:19 pm
Age: 27
Country: Costa Rica
City: Pital
Vehicle: 1991 Amigo

Re: 4JB1 Repair Questions

Postby 4JB1TCR » Thu Sep 29, 2016 6:26 am

geeves wrote:That looks like a factory chrome liner that has been honed. Its peeling at the top


You know, I never thought of that! I wondered how the crosshatching could be so clearly visible, and yet have so much wear at the top.
4JB1TCR
Isuzu Baby
 
Posts: 13
Joined: Wed Sep 07, 2016 11:19 pm
Age: 27
Country: Costa Rica
City: Pital
Vehicle: 1991 Amigo

Re: 4JB1 Repair Questions

Postby geeves » Thu Sep 29, 2016 6:45 am

You can get rebuild kits from the likes of aliexpress relatively cheaply but before you do anything I would pull the engine apart and see what you really have
Sanding your knuckles before starting work can help. That way you cant skin them
User avatar
geeves
Site Admin
 
Posts: 8962
Joined: Sun May 10, 2009 1:36 pm
Location: Rangiora
Age: 63
Country: NZ
City: Rangiora
Vehicle: 94 bighorn 4jg2
2013 Subaru XV

Re: 4JB1 Repair Questions

Postby 4JB1TCR » Sat Oct 01, 2016 3:22 am

Thanks. I hope to start the disassembly tomorrow. I can get a rebuild kit locally for a pretty good price. I will probably need to order a set of headbolts from Australia, as I can't find them here. They are in good shape, but I bent two, foolishly using them to attach a chain to hoist the engine.
4JB1TCR
Isuzu Baby
 
Posts: 13
Joined: Wed Sep 07, 2016 11:19 pm
Age: 27
Country: Costa Rica
City: Pital
Vehicle: 1991 Amigo

Re: 4JB1 Repair Questions

Postby geeves » Sat Oct 01, 2016 5:18 am

One thought before you do anything.
What are you going to bolt the engine to once its fixed?
My understanding is that the bell housing between the petrol and diesel engine is different and as its part of the gearboox casing a complete gearbox is required. Getting a diesel Mu gearbox in America could be a lot of fun. You could get a diesel bighorn gearbox but I dont know if the remote shifter bolts on from your Amigo box
Sanding your knuckles before starting work can help. That way you cant skin them
User avatar
geeves
Site Admin
 
Posts: 8962
Joined: Sun May 10, 2009 1:36 pm
Location: Rangiora
Age: 63
Country: NZ
City: Rangiora
Vehicle: 94 bighorn 4jg2
2013 Subaru XV

Re: 4JB1 Repair Questions

Postby 4JB1TCR » Sat Oct 01, 2016 7:59 am

It is going to be bolted to the original MUA 5 speed manual. I managed to score the front housing for a diesel transmission, brand new on Ebay in the USA. Why in the states I don't know, but it was there and I managed to get it for $200 US. It just got here last night.
4JB1TCR
Isuzu Baby
 
Posts: 13
Joined: Wed Sep 07, 2016 11:19 pm
Age: 27
Country: Costa Rica
City: Pital
Vehicle: 1991 Amigo

Re: 4JB1 Repair Questions

Postby 4JB1TCR » Sat Oct 01, 2016 8:06 am

Here it is, with the back plate from the engine lying on top to make sure it fits.
Image
4JB1TCR
Isuzu Baby
 
Posts: 13
Joined: Wed Sep 07, 2016 11:19 pm
Age: 27
Country: Costa Rica
City: Pital
Vehicle: 1991 Amigo

Re: 4JB1 Repair Questions

Postby 4JB1TCR » Tue Oct 04, 2016 1:41 am

Hello!
So I tore into it on on Saturday...
Image
Image

Doing things you're not supposed to do...
Image

Ready for the bottom end
Image
Image

Number 1 rod journal
Image
number 1 Piston
Image

Number 1 Rod bearings
Image
Image
4JB1TCR
Isuzu Baby
 
Posts: 13
Joined: Wed Sep 07, 2016 11:19 pm
Age: 27
Country: Costa Rica
City: Pital
Vehicle: 1991 Amigo

Re: 4JB1 Repair Questions

Postby 4JB1TCR » Tue Oct 04, 2016 1:57 am

Number 3 bearings
Image
Piston
Image
There is a tiny ding on the crank, which I think caused the scoring on the bearing.
Image
The crank is not discoloured, the different colours visible are reflections.

Can these cranks be machined?
4JB1TCR
Isuzu Baby
 
Posts: 13
Joined: Wed Sep 07, 2016 11:19 pm
Age: 27
Country: Costa Rica
City: Pital
Vehicle: 1991 Amigo

Re: 4JB1 Repair Questions

Postby 4JB1TCR » Tue Oct 18, 2016 1:31 am

No real update yet, I pulled the main bearing caps, and the bearings there look pretty good.

Another question here, what is the second solenoid on the injector pump for? The one with the green rubber cover... Photo attached.

Image
4JB1TCR
Isuzu Baby
 
Posts: 13
Joined: Wed Sep 07, 2016 11:19 pm
Age: 27
Country: Costa Rica
City: Pital
Vehicle: 1991 Amigo


Return to Engine

Who is online

Users browsing this forum: No registered users and 14 guests

cron